The present invention relates to the medical diagnostic and surgical arts. It finds particular application in conjunction with neurosurgery and will be described with particular reference thereto. However, it is to be appreciated, that the invention will also find application in conjunction with other medical procedures, industrial quality control procedures, and the like.
Three-dimensional diagnostic image data of the brain and other body portions are commonly available with CT scanners, magnetic resonance imagers, and other medical diagnostic equipment. These imaging modalities provide structural detail with a resolution of a millimeter or better.
Various stereotaxy procedures have been developed which require extreme accuracy. Typical neurosurgical procedures included guided-needle biopsies, shunt placements, craniotomies for lesion or tumor resection, and the like. A three-dimensional "localizer" is attached to the patient's skull. The localizer is a mechanical device with precisely known geometry and dimensions for guiding or positioning surgical instruments. The localizer is commonly attached to a ring or frame of metal or plastic from which the name "framed" stereotaxy has evolved. This frame is typically affixed to the patient using various mounting hardware methods that include sharp points or pins that pierce the skin and locate into the skull. The localizer is then mounted onto a frame. The localizer and frame provide the surgeon with the ability to position surgical instruments mechanically with a mechanical accuracy of a millimeter or better. However, anatomically, accuracy is somewhat less due to inaccuracies in the diagnostic imaging and patient motion.
One of the difficulties that has arisen is accurately coordinating the coordinate system of the patient's skull or stereotaxy localizer with the coordinate system of the diagnostic data. One solution has been to image the patient with the stereotaxic frame attached. Because the stereotaxic frame appears in the resultant images, the surgeon is provided with a frame of reference in the images. Although relatively accurate in coordinating the two frames of reference, the use of the frame has numerous drawbacks including the need to mount the frame to the patient's head for both the imaging and the surgical procedures and the associated cost.
The present invention provides a new and improved technique which simply and painlessly coordinates the coordinate system of three-dimensional image data obtained from one or more imaging modalities with the coordinate system of the patient prior to or during surgery.